Note: Descriptions are shown in the official language in which they were submitted.
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DESCRIPTION
DETERIORATION ANALYSIS METHOD
TECHNICAL FIELD
[0001]
The present invention relates to a deterioration
analysis method for analysis of deterioration of a polymer
material.
BACKGROUND ART
[0002]
For analyzing a change in chemical state of a polymer
material containing at least one diene rubber caused by
deterioration, for example, an infrared spectroscopy (FT-
IR), nuclear magnetic resonance analysis (NMR), and X-ray
photoelectron spectroscopy (XPS) and the like are commonly
employed. Though FT-IR or NMR allows a detailed analysis
of the chemical state, the obtained information is bulk
information and therefore it is difficult to analyze in
detail the chemical state after deterioration which starts
at a sample surface.
[0003]
On the other hand, XPS is a surface-sensitive method
and is therefore thought to be effective for analysis of a
change in chemical state caused by deterioration. As one
example of analysis and evaluation of deterioration by XPS,
Fig. 1 shows the results of XPS measurement of the ls
orbital of carbon in fresh butadiene rubber (BR), ozone-
deteriorated BR, and oxygen-deteriorated BR (carbon K-shell
absorption edge of BR).
[0004]
As shown in Fig. 1, in the XPS measurement, the peak
of C.--C bond (double bond) and the peak of C-C bond (single
bond) overlap each other at around 285 eV, and therefore
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the chemical states of the different groups cannot be
distinguished. Hence, it is difficult to determine the
amount of C=C bonds (double bonds) that is reduced by
deterioration. Moreover, in Fig. 2 showing the results of
XPS measurement of the oxygen K shell absorption edge of
BR, no difference is found in the spectra between the
ozone-deteriorated BR and oxygen-deteriorated BR. Hence, a
detailed analysis of deterioration by XPS is difficult.
[0005]
Meanwhile, measurement of X-ray absorption spectra of
polymers has also been carried out as disclosed in Non
Patent Literatures 1 to 3. However, no disclosure is found
in any literatures including these non patent literatures
that deterioration factors can be distinguished based on
the X-ray absorption spectra.
CITATION LIST
NON PATENT LITERATURE
[0006]
Non Patent Literature 1: 0. Dhez, H. Ade, S. G.
Urquhart. J. Electron Spectrosc. Relat. Phenom., 2003, 128,
85-96
Non Patent Literature 2: Robert J. Klein, Daniel A.
Fischer, and Joseph L. Lenhart. Langmuir., 2008, 24, 8187-
8197
Non Patent Literature 3: Toshihiro Okajima, Hyomen kagaku
(Surface Science), 2002, Vol. 23, No. 6, 356-366
SUMMARY OF INVENTION
TECHNICAL PROBLEM
[0007]
The present invention aims to provide a deterioration
analysis method which can solve the above problems and
allows a detailed analysis of deterioration, especially
deterioration of surface conditions, of a polymer material.
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SOLUTION TO PROBLEM
[0008]
The present invention relates to a deterioration
analysis method, including irradiating a polymer material
with high intensity X-rays, and measuring X-ray absorption
while varying the energy of the X-rays, to analyze
deterioration of the polymer.
[0009]
The polymer material is preferably a rubber material
containing at least one diene rubber, or a composite
material combining the rubber material and at least one
resin.
The high intensity X-rays preferably have a number of
photons of 107 (photons/s) or more and a brilliance of le'
(photons/s/mrad2/mm2/0.1thw) or more. Also, an energy
range scanned with the high intensity X-rays is preferably
4000 eV or less.
[0010]
The deterioration analysis method preferably
includes: calculating normalization constants a and p using
Equation 1 below based on X-ray absorption spectra obtained
by scanning over a required range of high intensity X-ray
energies at the carbon K-shell absorption edge within the
range of 260 to 400 eV; performing waveform separation of
the X-ray absorption spectra at the carbon K-shell
absorption edge corrected with the normalization constants
a and p to obtain peak areas attributed to n* transition at
around 285 eV; and determining a degree of deterioration
using Equation 2 below with the obtained peak areas:
(Equation 1)
[total area of X-ray absorption spectrum over measurement
range of sample before deterioration] x a = 1, and
[total area of X-ray absorption spectrum over measurement
range of sample after deterioration] x 13 = 1; and
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4
(Equation 2)
[1-[(peak area of n* after deterioration) x ]/{(peak area
of n* before deterioration) x a]] x 100 . degree (96) of
deterioration.
In the deterioration analysis method, peak
intensities may be used instead of the peak areas.
[0011]
The deterioration analysis method preferably
includes: performing waveform separation of an X-ray
absorption spectrum at the oxygen K-shell absorption edge
obtained by scanning over a range of high intensity X-ray
energies of 500 to 600 eV; and calculating contribution
rates of oxygen deterioration and ozone deterioration using
Equation 3 below, wherein the oxygen deterioration
corresponds to a peak on the low energy side with a peak
top energy in the range of 532 to 532.7 eV, and the ozone
deterioration corresponds to a peak on the high energy side
with a peak top energy in the range of 532.7 to 534 eV:
(Equation 3)
[peak area of oxygen deterioration]/[(peak area of ozone
deterioration) + (peak area of oxygen deterioration)] x 100
= contribution rate (%-) of oxygen deterioration, and
[peak area of ozone deterioration]/[(peak area of ozone
deterioration) + (peak area of oxygen deterioration)] x 100
= contribution rate (96) of ozone deterioration.
In the deterioration analysis method, peak
intensities may be used instead of the peak areas.
[0012]
The deterioration analysis method preferably
includes: determining a normalization constant y using
Equation 4 below based on an X-ray absorption spectrum at
the carbon K-shell absorption edge after deterioration; and
correcting a total peak area of the oxygen K-shell
absorption edge with the normalization constant 7 to
determine the amount of oxygen and ozone bonded to the
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polymer material:
(Equation 4)
[total area of X-ray absorption spectrum at carbon K-shell
absorption edge] x 7= 1, and
5 [peak area of oxygen K-shell absorption edge] x y= amount
(index) of oxygen and ozone bonded.
ADVANTAGEOUS EFFECTS OF INVENTION
[0013]
Since the deterioration analysis method according to
the present invention includes irradiating a polymer
material with high intensity X-rays, and measuring X-ray
absorption while varying the energy of the X-rays, to
analyze deterioration of the polymer, the method can
analyze in detail the deterioration, especially
deterioration of surface conditions, of a polymer material.
Accordingly, with regard to the deterioration of a polymer
material, the degree (96) of deterioration, the contribution
rates of oxygen deterioration and ozone deterioration, and
the amount of oxygen and ozone bonded to the polymer
material (deterioration indicator) can be measured.
BRIEF DESCRIPTION OF DRAWINGS
[0014]
Fig. 1 is a graph showing the results of XPS
measurement of the is orbital of carbon in fresh butadiene
rubber (BR), ozone-deteriorated BR, and oxygen-deteriorated
BR.
Fig. 2 is a graph showing the results of XPS
measurement of the oxygen K-shell absorption edge in ozone-
deteriorated butadiene rubber and oxygen-deteriorated
butadiene rubber.
Fig. 3 is a graph (before normalization) showing the
results of NEXAFS measurement of the carbon K-shell
absorption edge in fresh butadiene rubber, a sample
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subjected to ozone deterioration for seven hours, and a
sample subjected to oxygen deterioration for a week.
Fig. 4 is a graph (after normalization) showing the
results of NEXAFS measurement of the carbon K-shell
absorption edge in fresh butadiene rubber, a sample
subjected to ozone deterioration for seven hours, and a
sample subjected to oxygen deterioration for a week.
Fig. 5 is a graph showing the results of NEXAFS
measurement around the oxygen K-shell absorption edge in a
butadiene rubber sample subjected to ozone deterioration
for seven hours and a sample subjected to oxygen
deterioration for a week.
Fig. 6 is a graph showing the results of NEXAFS
measurement around the oxygen K-shell absorption edge in a
butadiene rubber sample subjected to complex deterioration
(both oxygen deterioration and ozone deterioration).
Fig. 7 is a graph (after normalization) showing the
results of NEXAFS measurement in butadiene rubber samples
subjected to ozone deterioration for one hour and seven
hours.
DESCRIPTION OF EMBODIMENTS
[0015]
The deterioration analysis method of the present
invention includes irradiating a polymer material with high
intensity X-rays, and measuring X-ray absorption while
varying the energy of the X-rays, to analyze deterioration
of the polymer. Known deterioration factors of polymer
materials such as rubber include deterioration of polymer
molecular chains and crosslinked structures by ultraviolet
light, oxygen, ozone, heat and the like. To improve the
resistance to deterioration, it is important to know what
factor is responsible and how the polymer molecular chains
and crosslinked structures then change.
[0016]
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In this respect, the deterioration analysis method
focuses on the use of high intensity X-rays to analyze the
chemical state in greater detail than the conventional
methods such as FT-IR, NMR, Raman scattering spectroscopy,
and XPS. In this method, while the energy of high
intensity X-rays is varied, fresh and deteriorated polymer
materials are irradiated with the X-rays to measure the X-
ray absorption, and then the obtained spectra are compared,
whereby the deterioration of the deteriorated polymer
material can be analyzed.
[0017]
Specifically, a method may be employed in which an X-
ray absorption spectrum around the absorption edge of a
specific target element is measured using high intensity X-
rays (NEXAFS: Near Edge X-ray Absorption Fine Structure).
Since the soft X-ray region includes absorption edges of
light elements, the chemical state of soft materials can be
analyzed in detail.
[0018]
Since X-ray energy is used for scanning in the NEXAFS
method, a continuous X-ray generator is needed as the light
source. For a detailed analysis of the chemical state, an
X-ray absorption spectrum with high S/N and S/B ratios
needs to be measured. For this reason, a synchrotron is
suitably used in the NEXAFS measurement because it emits X-
rays having a brilliance of at least 101
(photons/s/mrad2/mm2/0.196bw) and is a continuous X-ray
source. It is to be noted that the symbol bw indicates a
band width of X-rays emitted from a synchrotron.
[0019]
The brilliance (photons/s/mrad2/mm2/0.1%-bw) of the
high intensity X-rays is preferably 1010 or more, and more
preferably 1012 or more. The upper limit thereof is not
particularly limited, and the X-ray intensity used is
preferably low enough not to cause radiation damage.
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[0020]
The number of photons (photons/s) of the high
intensity X-rays is preferably 107 or more, and more
preferably 109 or more. The upper limit thereof is not
particularly limited, and the X-ray intensity used is
preferably low enough not to cause radiation damage.
[0021]
The energy range scanned with the high intensity X-
rays is preferably 4000 eV or less, more preferably 1500 eV
or less, and still more preferably 1000 eV or less. With
an energy range exceeding 4000 eV, the deterioration of a
target polymer composite material may not be analyzed. The
lower limit is not particularly limited.
[0022]
The measurement can be carried out as follows. A
sample placed in an ultra-high vacuum is irradiated with
soft X-rays so that photoelectrons are emitted. Then
electrons flow from the ground to the sample so as to
compensate for the emitted photoelectrons, and this sample
current is measured. Accordingly, such measurement is
surface-sensitive but can only measure samples that do not
produce gas in vacuo and are electrically conductive.
Therefore, in the past, crystals and molecular adsorption
have been mainly studied through the measurement, whereas
rubber samples that are likely to produce gas and are
insulating materials have hardly been studied.
[0023]
However, the ESCA method, which is similarly surface-
sensitive, observes the inner shells of an atom and thus is
difficult to distinguish the deteriorations of a polymer in
detail. In contrast, the NEXAFS method observes the outer
shells of an atom which are affected by the reaction
between atoms, and thus allows greater reflection of the
impact of an element bonded to the target element than the
ESCA method. Therefore, the present inventors have
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9
considered that the NEXAFS method can distinguish
individual molecular states and thus can distinguish
deterioration factors, thereby completing the present
invention.
[0024]
More specifically, the measurement can be conducted
by the following method.
A sample mounted on a sample holder is placed in a
vacuum chamber for X-ray absorptiometry. Then the sample
is irradiated with continuous X-rays that are emitted from
a synchrotron and subsequently monochromatized with a
monochromator. At that time, secondary electrons and
photoelectrons escape from the sample surface into vacuum,
and then electrons are replenished from the ground to
compensate for the loss of electrons. Then, the X-ray
absorption (pL) is calculated using Equation 5 below,
wherein the X-ray absorption intensity I represents a
current flowing from the ground, and the incident X-ray
intensity Io represents a current from a gold mesh provided
in an optical system of a beamline (electron yield method).
It should be noted that the equation of Lambert-Beer is
applicable to the method, and Equation 5 is thought to hold
approximately in the case of the electron yield method:
(Equation 5)
Io(E)/I(E) exp(pL) pL (E: energy of X-rays, L:
thickness of sample, p: absorption coefficient).
[0025]
The following three methods are typically used as the
NEXAFS measurement. In examples of the present invention,
the electron yield method is employed but is not intended
to limit the scope of the invention. Various detection
methods may be employed and may be combined for
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simultaneous measurement.
[0026]
(Transmission method)
This is a method of detecting the intensity of the X-
5 rays having passed through a sample. For measurement of
the intensity of transmitted light, for example, a
photodiode array detector may be used.
[0027]
(Fluorescence method)
10 This is a method of detecting fluorescent X-rays
generated when a sample is irradiated with X-rays. In the
case of the transmission method, if the X-ray absorption of
an element contained in a small amount in a sample is
measured, then a spectrum with a poor S/B ratio is obtained
because the signal is small and the background is high due
to X-ray absorption by an element contained in a large
amount in the sample. In contrast, in the case of the
fluorescence method (especially when an energy dispersive
detector or the like is used), only the fluorescent X-rays
from the target element can be measured and thus the
element contained in a large amount has a small influence.
Hence, the method is effective in order to measure the X-
ray absorption spectrum of an element contained in a small
amount. In addition, since fluorescent X-rays have high
penetrating power (low interaction with substances),
fluorescent X-rays generated inside the sample can be
detected. Hence, the method is the second most suitable
method for obtaining bulk information after the
transmission method.
[0028]
(Electron yield method)
This is a method of detecting a current flowing when
a sample is irradiated with X-rays. Thus, the sample needs
to be an electrically conductive material. Since polymer
materials are insulating materials, X-ray absorption
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measurement of a polymer material has mostly been carried
out by putting a very thin layer of a sample on a substrate
by deposition, spin-coating or the like. In the present
invention, when a polymer material is processed (cut) with
a microtome to 100 pm or less, preferably to 10 pm or less,
more preferably to 1 pm or less, and still more preferably
to 500 nm or less, high S/B and S/N ratios can be achieved
through the measurement.
[0029]
The electron yield method features surface
sensitivity (information from the sample surface to a depth
of approximately several nanometers). Irradiation of a
sample with X-rays causes escape of electrons from
elements. Since electrons have a great interaction with
substances, their mean free path in a substance is short.
[0030]
The X-ray absorption spectra of a polymer material
can be measured by the electron yield method and then
analyzed to assay the degree (%) of deterioration, the
contribution rates (%) of oxygen deterioration and ozone
deterioration, and the amount of oxygen and ozone bonded
(deterioration indicator). These assays are described
below.
[0031]
The deterioration analysis method may include:
calculating normalization constants a and p using Equation
1 below based on X-ray absorption spectra obtained by
scanning over a required range of high intensity X-ray
energies at the carbon K-shell absorption edge within the
range of 260 to 400 eV; performing waveform separation of
the X-ray absorption spectra at the carbon K-shell
absorption edge corrected with the normalization constants
a and p to obtain peak areas attributed to n* transition at
around 285 eV; and determining a degree of deterioration
using Equation 2 below with the obtained peak areas:
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(Equation 1)
[total area of X-ray absorption spectrum over measurement
range of sample before deterioration] x a = 1, and
[total area of X-ray absorption spectrum over measurement
range of sample after deterioration] x = 1; and
(Equation 2)
[1-[(peak area of n* after deterioration) x P]/[(peak area
of n* before deterioration) x a]] x 100= degree of
deterioration (96).
In this manner, the degree (96) of deterioration of a
polymer after deterioration can be obtained to allow
analysis of the deterioration rate. In the method for
determining the degree of deterioration, the range of high
intensity X-ray energies is preferably 260 to 350 eV. In
the method for determining the degree of deterioration, the
background is assessed based on a slope before the
absorption edge and subtracted, prior to the calculation of
Equation 1.
[0032]
In the method for determining the degree of
deterioration, the total area of the X-ray absorption
spectrum in Equation 1 is the integral of the spectrum over
a measurement range. The energy range can be changed
according to the measurement conditions and the like.
[0033]
The method for determining the degree of
deterioration is more specifically described using an
example in which fresh BR, a sample subjected to ozone
deterioration for seven hours, a sample subjected to oxygen
deterioration for a week are used.
Fig. 3 shows the results of NEXAFS measurement of the
carbon K-shell absorption edge in these samples. As shown
in Fig. 3, deteriorated samples each have a smaller n* peak
at around 285 eV than the fresh sample; however, the NEXAFS
method is difficult to perform an absolute measurement
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because subtle changes in the distance from the light
source to the sample and the like affect the magnitude of
the X-ray absorption spectrum. For this reason, the
results of NEXAFS measurement of the carbon K-shell
absorption edge cannot be simply compared between samples.
[0034]
For comparison between the X-ray absorption spectra
of the measured samples, normalization is carried out as
follows (the X-ray absorption spectrum of each sample is
corrected for direct comparison). Since the amount of
carbon shell X-ray absorption is not changed before and
after deterioration, the peak area of the carbon K-shell
absorption edge is normalized to 1 using Equation 1. In
other words, normalization constants a and p are first
calculated using Equation 1 based on the X-ray absorption
spectra before normalization, and then the spectra are
corrected (normalized) by multiplying the X-ray absorption
spectra before normalization by a and p, whereby the n*
peaks of the samples can be directly compared.
[0035]
Fig. 4 shows the thus-obtained spectra at the carbon
K-shell absorption edge after normalization. The degree of
deterioration is determined using Equation 2 based on the
normalized spectra. The degree of deterioration is the
n*peak reduction from before to after deterioration, and
indicates the deterioration rate (%) of a sample.
[0036]
In the method for determining the degree of
deterioration, the degree of deterioration can be similarly
determined when peak intensities are used instead of the
peak areas in Equation 2.
[0037]
Other examples of the deterioration analysis method
include a method that includes: performing waveform
separation of an X-ray absorption spectrum at the oxygen K-
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shell absorption edge obtained by scanning over a range of
high intensity X-ray energies of 500 to 600 eV; and
calculating contribution rates of oxygen deterioration and
ozone deterioration using Equation 3 below, wherein the
oxygen deterioration corresponds to a peak on the low
energy side with a peak top energy in the range of 532 to
532.7 eV, and the ozone deterioration corresponds to a peak
on the high energy side with a peak top energy in the range
of 532.7 to 534 eV:
(Equation 3)
[peak area of oxygen deterioration]/[(peak area of ozone
deterioration) + (peak area of oxygen deterioration)] x 100
= contribution rate (96) of oxygen deterioration, and
[peak area of ozone deterioration]/[(peak area of ozone
deterioration) + (peak area of oxygen deterioration)] x 100
= contribution rate (9v) of ozone deterioration.
In this manner, the contribution rates (96) of oxygen
deterioration and ozone deterioration in a polymer material
after deterioration can be obtained to allow analysis of
the contribution rate of each deterioration factor. In the
method for calculating the contribution rates, the
background is assessed based on a slope before the
absorption edge and subtracted, prior to the calculation of
Equation 3.
[0038]
The method for calculating the contribution rates is
more specifically described using an example in which fresh
BR, a sample subjected to ozone deterioration for seven
hours, and a sample subjected to oxygen deterioration for a
week are used.
First, Fig. 5 shows the results of NEXAFS measurement
around the oxygen K-shell absorption edge in the fresh BR,
the sample subjected to ozone deterioration for seven
hours, and the sample subjected to oxygen deterioration for
a week as shown in Fig. 1. As shown in the figure, the
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ozone-deteriorated sample has a peak at 532.7 to 534 eV,
and the oxygen-deteriorated sample has a peak at 532 to
532.7 eV. It is found out that, of these two peaks, the
peak on the high energy side is attributed to ozone
5 deterioration and the peak on the low energy side is
attributed to oxygen deterioration.
[0039]
Fig. 6 shows the results of NEXAFS measurement in a
sample subjected to complex deterioration (both oxygen
10 deterioration and ozone deterioration). As shown in Fig.
6, a peak with two shoulders was detected at 532 to 534 eV.
This is thought to be due to overlapping of the peak on the
low energy side (532 to 532.7 eV) attributed to oxygen
deterioration and the peak on the high energy side (532.7
15 to 534 eV) attributed to ozone deterioration. Hence, peak
separation was performed and then the contribution rates of
oxygen deterioration and ozone deterioration were
determined using Equation 3. In this manner, the sample
subjected to both oxygen deterioration and ozone
deterioration can be analyzed for the proportion of each of
the two deterioration factors, oxygen deterioration and
ozone deterioration.
[0040]
In the method for calculating the contribution rates,
the contribution rates of oxygen deterioration and ozone
deterioration can be similarly determined when peak
intensities are used instead of the peak areas in Equation
3.
[0041]
Still other examples of the deterioration analysis
method include a method that includes: determining a
normalization constant y using Equation 4 below based on an
X-ray absorption spectrum at the carbon K-shell absorption
edge after deterioration; and correcting a total peak area
of the oxygen K-shell absorption edge with the
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normalization constant 7 to determine the amount of oxygen
and ozone bonded to the polymer material:
(Equation 4)
[total area of X-ray absorption spectrum at carbon K-shell
absorption edge] x 7 = 1, and
[peak area of oxygen K-shell absorption edge] x 7 . amount
(index) of oxygen and ozone bonded.
In this manner, the amount of oxygen and ozone bonded
to a polymer material due to deterioration can be measured
and used as a deterioration indicator.
[0042]
In the method for determining the bonded amount, the
total peak area is the integral of the spectrum over a
measurement range. The energy range can be changed
according to the measurement conditions and the like.
[0043]
The method for determining the bonded amount is more
specifically described using an example in which BR samples
subjected to ozone deterioration for an hour and seven
hours are used.
Fig. 7 shows the results of NEXAFS measurement in
these samples. These spectra are each obtained by
calculating a normalization constant 7 using Equation 4
based on an X-ray absorption spectrum at the carbon K-shell
absorption edge, and carrying out normalization as
mentioned above. The normalized peak area of the oxygen K-
shell absorption edge is thought to correspond to the
amount of oxygen and ozone bonded. As shown in the figure,
the sample subjected to deterioration for seven hours shows
a larger area than the sample subjected to deterioration
for an hour, and therefore the resulting value can be used
as a deterioration index. A larger number of the
deterioration index indicates a larger amount of oxygen
bonded to the polymer material due to deterioration. In
this manner, the deterioration rate when oxygen and ozone
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are bonded to a polymer material can be measured based on
the rate of increase in the peak area of the oxygen K-shell
absorption edge.
[0044]
The method of the present invention mentioned above
can be carried out using, for example, the BL12 beamline at
Kyushu Synchrotron Light Research Center (SAGA-LS).
[0045]
The polymer material usable in the present invention
is not particularly limited, and may be any conventionally
known material. For example, the polymer material may
suitably be a rubber material containing at least one diene
rubber, or a composite material combining the rubber
material and at least one resin. Examples of the diene
rubber include polymers containing a double bond, such as
natural rubber (NR), isoprene rubber (IR), butadiene rubber
(BR), styrene butadiene rubber (SBR), acrylonitrile
butadiene rubber (NBR), chloroprene rubber (CR), butyl
rubber (IIR), halogenated butyl rubber (X-IIR), and styrene
isoprene butadiene rubber (SIBR).
[0046]
The resin is not particularly limited, and may be a
general purpose resin used in the rubber industry field.
Examples thereof include petroleum resins such as C5
aliphatic petroleum resins and cyclopentadiene petroleum
resins. The deterioration analysis method of the present
invention can suitably be applied to these materials.
EXAMPLES
[0047]
The present invention is more specifically described
referring to, but not limited to, examples.
[0048]
(Examples and Comparative Examples)
Deteriorated samples used in examples and comparative
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examples were prepared using the rubber materials and
deterioration conditions mentioned below. For measurement
by the NEXAFS method, each sample was processed to have a
thickness of 100 pm or less using a microtome. Then, to
avoid any influence of oxygen other than that due to
deterioration, the prepared samples were stored in a vacuum
desiccator.
(Rubber materials)
IR: Nipol IR 2200 from ZEON CORPORATION
BR: Ubepol BR 130B from UBE INDUSTRIES, LTD.
SBR: Nipol 1502 from ZEON CORPORATION
SIBS: SIBSTAR 102T from Kaneka Corporation
Sample after driving in US: Tire that had been driven in US
Sample after driving in Japan: Tire that had been driven in
Japan
(Deterioration conditions)
Ozone deterioration: 40 C, 50 pphm (1 hour or 7 hours)
Oxygen deterioration: 80 C, oxygen:nitrogen = 5:1 (168
hours)
[0049]
(Used devices)
NEXAFS: NEXAFS measurement device provided with the
beamline BL12 at Kyushu Synchrotron Light Research Center
(SAGA-LS)
XPS: AXIS Ultra from Kratos Surface Analysis
[0050]
The degree (9) of deterioration of each sample was
determined through the following deterioration rate
analysis with NEXAFS. Also, the contribution rates (96) of
oxygen and ozone deterioration were determined through the
following deterioration contribution rate analysis. In
addition, the deterioration indicator (index) was
determined through the following deterioration indicator
determination.
The measurement conditions of NEXAFS used here were
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as follows.
Brilliance: 5 x 1012 photons/s/mrad2/mm2/0 ..1%bw
Number of photons: 2 x 109 photons/s
[0051]
(Deterioration rate analysis)
Scanning was performed over a range of high intensity
X-ray energies of 260 to 400 eV to obtain X-ray absorption
spectra at the carbon K-shell absorption edge.
Normalization constants a and 13 were calculated using
Equation 1 based on the spectra over the required range of
260 to 350 eV, and then the spectra were normalized
(corrected) with the obtained constants. The normalized
spectra were subjected to waveform separation, and then the
degree (96) of deterioration was determined using Equation 2
based on the resulting peak areas attributed to n*
transition at around 285 eV.
[0052]
(Deterioration contribution rate analysis)
Scanning was performed over a range of high intensity
X-ray energies of 500 to 600 eV to obtain an X-ray
absorption spectrum at the oxygen K-shell absorption edge.
The spectrum was subjected to waveform separation, and then
the contribution rates of oxygen deterioration and ozone
deterioration were calculated using Equation 3, wherein the
oxygen deterioration corresponds to a peak on the low
energy side with a peak top at 532 to 532.7 eV, and the
ozone deterioration corresponds to a peak on the high
energy side with a peak top at 532.7 to 534 eV.
[0053]
(Deterioration indicator determination)
The normalization constant 7 was determined using
Equation 4 based on the X-ray absorption spectrum at the
carbon K-shell absorption edge after deterioration obtained
in the deterioration rate analysis. The total peak area of
the oxygen K-shell absorption edge was corrected
CA 02815807 2014
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(normalized) with the constant, whereby the amount of
oxygen and ozone bonded to the polymer material
(deterioration indicator) was determined based on Equation
4.
[0054]
In Comparative Examples 1 to 4, the deteriorated
samples were evaluated using XPS.
Table 1 shows the results obtained in the above
analyses.
[0055]
[Table 1]
,
CA 02815807 2013-04-24
. ' 21
C om parative Exam ph 1 Exam ph 1 Exam ph 2 Exam ph 3
M easurem ent m ethod XPS NEXAFS NEXAFS
NEXAFS
M aterialnam e Ili JR /
IR
D eterioration tin e 0-0/ozone 1 1 7
Deterioration tine 00/hot oxygen - -
168
Con Ubution rate %) of ozone deterbratbn Not cahuhbh _ 100
100 0
Contrbutbn rate 6)) of oxygen deterioration Not caEulabh
0 0 100
Degree %) of deterbration N ot caEuhbh 78 100
23
Deterioration hdhator Not cahulibh 0.43 0.56
0.22
Comparative Exam ph 2 Exam ph 4 Exam ph 5 Exam ph 6
M easurem ent m ethod XPS NEXAFS NEXAFS
NEXAFS
M aterhlnam e BR BR BR
BR
D eterioratbn tine (h)/ozone 1 1 7
.D eterbratbn tine 0-0/hot oxygen
168
C on Ltbutbn rate %) of ozone deterbration N ot cahulabh
100 100 0
Con trimtbn rate %) of oxygen deterioration Not cabulabh
0 0 100
Degree %) of deterbration Not caEu hbh 57 88
19
D eterioratbn hdhator Not cahuhbh 0.22 0.43
0.40
Comparative Exam ph 3 Exam ph 7 Exam ph 8 Exam_ph 9
M easurem ent m ethod XPS NEXAFS NEXAFS
NEXAFS
M a-ter-hi nam e SBR SBR SBR
SBR
D eterioratbn tine 0-0/ozone 1 1 7
-
D eterioratbn tine 0-0/hot oxygen -
168
Con Aution rate 60 of ozone deterbratbn Not cahuhbh 100 100
0
Con trbution rate 6) of oxygen deterbratbn Not calcuhbh
0 0 100
Degree 60 of deterioration Not cahulabh 12 37
5
D eterbratbn hdicator Not cabulabh 0.18 0.25
0.10
Comparative Exam ph 4 Exam ph 10 Exam ph 11
M easurem ent m ethod XPS NEXAFS NEXAFS
M ateridnam e 1R/SIBS E/SIBS , 1R/SIBS
D eterbratbn tin e 0-0/ozone 1 7
D eterioration tin e (11)/hot oxygen - 168 ,
C ontrbutbn rate () of ozone deterioration Not caEulabh 0
100
Contrbution rate &) of oxygen deterbratbn Not calcuhbh 100 0
Degree N) of deterioration Not cahulabh 16 85
D eterbratbn hdhator Not calcuhbh 0.13 0.51
Exam ph 12 Exam ple 13
Measurement method NEXAFS NEXAFS
Sam ph
Sam ph
M aterialnam e after driviig
after drivhg in US
h Japan
D eterbration tin e (h)/ozone -
D eterioratbn tin e 00/hot oxygen -
Con Ulm tion rate &) of ozone deterbration 55 10
Con trbution rate 60) of oxygen deterbration 45 90
Degree %) of deterioration 45 25
D eterbratbn hdhator 0.63 0.21
CA 02815807 2014
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[0056]
In Comparative Examples 1 to 4 using XPS, none of the
contribution rates of ozone deterioration and oxygen
deterioration, the degree of deterioration and the
deterioration indicator (index) of the deteriorated samples
could be analyzed. In contrast, in examples using NEXAFS,
all of these items could be analyzed. The results shows
that, in Examples 1, 2, 4, 5, 7, 8 and 11 subjected to only
ozone deterioration, the contribution rate of ozone
deterioration was 100%, and, in Examples 3, 6, 9 and 10
subjected to only oxygen deterioration, the contribution
rate of oxygen deterioration was 100%. Additionally, the
results of the degree of deterioration and the
deterioration indicator in these examples had excellent
correlations. In Examples 12 and 13 where samples
subjected to both ozone deterioration and oxygen
deterioration were used, the contribution rate of each
deterioration could be analyzed. Therefore, the evaluation
according to the present invention was demonstrated to be
effective.
